[MLDSA] zeroize mem_inst2 memory exceed depth

[nelson-ou]

Hi Caliptra Team
A minor observation.
MLDSA zeroizing mem_inst2, the write_address increment from 0 to 1472, one over the depth.
It should be from 0 to 1471.

[nelson-ou]

Hi @Nitsirks
Think this could be fixed easily, rather than mark for future enhancement?

[Nitsirks]

Overview

Depending on the memory implementation used for simulation, integrators may see warnings or errors due to the address wrapping beyond the max depth. The zeroization flow walks every address and writes zeroes to the memory, the wrapped address will alias to some address and get zeroized again. It will not pose any functional issues.

Workaround

Integrators should suppress these warnings or errors during zeriozation.

Severity

This issue is not a functional bug and fixing this issue in patch releases risks unnecessarily complicating ECO flows for integrators already in the process of implementing Adams Bridge or Caliptra. A fix has been made to main and will be included in a future major or minor release. See #236